Shuttering and reinforcing element for concrete structures

ABSTRACT

The invention relates to structural elements used as shuttering and as reinforcing elements in the production of concrete structures. The structural elements are basically plate-like in form and built up from an assembly of longitudinal rods in one plane, the rods being connected by a series of cross-ribs of strip form, the portion of each strip between each rod being curved out of the plane of the plate, the curvature of alternate cross-ribs being in opposed directions. The longitudinal rods are of reinforcing steel while the strips for the cross-ribs may be of steel or synthetic material and all cross-ribs may be fastened to the same side of the longitudinal rods. Where cross-ribs of synthetic material are used additional strengthening ribs of strip-like or rod-like reinforcing steel also arranged transversely to the longitudinal rods may be connected to the latter.

United States Patent 1 Glatz 1 June 19, 1973 SHUTTERING AND REINFORCING ELEMENT FOR CONCRETE STRUCTURES [75] Inventor: Horst Glatz, Eldagsen Hanover,

Germany [73] Assignee: Deumu Deutsche Erz-und MetaIl-Union Gesellschaft mit beschrankter Haftung, Hanover, Germany [22] Filed: Mar. 16, 1971 [21] Appl. No.: 124,826

[30] Foreign Application Priority Data FOREIGN PATENTS OR APPLICATIONS 1,041,122 9/1966 Great Britain..... 52/669 799,090 3/1936 France 52/669 Primary Examiner-Henry C. Sutherland Attorney-Herman, Davidson & Berman [57] ABSTRACT The invention relates to structural elements used as shuttering and as reinforcing elements in the production of concrete structures. The structural elements are basically plate-like in form and built up from an assembly of longitudinal rods in one plane, the rods being connected by a series of cross-ribs of strip form, the portion of each strip between each rod being curved out of the plane of the plate, the curvature of alternate cross-ribs being in opposed directions. The longitudinal rods are of reinforcing steel while the strips for the cross-ribs may be of steel or synthetic material and all cross-ribs may be fastened to the same side of the longitudinal rods. Where cross-ribs of synthetic material are used additional strengthening ribs of strip-like or rodlike reinforcing steel also arranged transversely to the longitudinal rods may be connected to the latter.

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ATTORNEYS.

SHUTTERING AND REINFORCING ELEMENT FOR CONCRETE STRUCTURES BACKGROUND OF THE INVENTION Known structural elements serving as lost shuttering and reinforcement are made of sheet steel in plate form which has been shaped and stamped to give corrugations which provide longitudinal ribs connected by cross-ribs which are deflected perpendicular to the plane of the plate alternately in the one and other direction.

Such shuttering and reinforcing elements are for example used in the production of a steel reinforced concrete structure in tunnels or mines but can also be employed in other structural work below ground level. The plate-shaped structural elements are arranged at the limiting surfaces of the steel reinforced concrete body to be produced, as a kind of shuttering and filled with a concrete of high consistency. The concrete partially flows out through openings between the curved cross-ribs and embeds therein the plates serving as shuttering in such a way in the concrete mass that the plates, serving first as shuttering, act as reinforcement after the hardening of the concrete. Instead of filling in with concrete other processes are known in which the concrete is sprayed from outside through the openings of the plates serving as shuttering wherein the plates after the filling up of the hollow spaces lying behind them are likewise embedded in the concrete mass and then serve as reinforcement. In another method the concrete is first sprayed on from outside onto the plates until all the openings of the plates are closed. After the setting of the sprayed-on concrete the space behind the plates is then packed with concrete through special filling openings previously left open. Also in this case plates serving initially as shuttering are embedded in the concrete in such a way that they act as reinforcement after hardening of the concrete. These known shuttering and reinforcement elements have the disadvantage that they can absorb in the longitudinal direction of the longitudinal ribs only relative slight tension forces, since the corrugations of the sheet which serve as longitudinal ribs are weakened at the connection positions of the cross-ribs by notch effect. The notch effect is thus accordingly intensified in that the neighboring cross-ribs at the connection position are curved in opposed directions.

In consequence of the relatively slight tensile strength of the longitudinal ribs of the structural element made from sheet the employment of these structure elements in structures above ground level is problematical. The only possible way for the known structural elements to attain a sufficient tensile strength in the longitudinal ribs lies in enlarging the cross-section of the longitudinal rib corrugations. This can be done either by a considerable broadening of the corrugations or by the selection of a greater sheet thickness. There are practical limits to the broadening of the corrugations in that with the greater breadths a troublefree embedding of the longitudinal ribs is no longer assured. In addition a considerable increase of the weight of the structural element occurs. The weight increase is even substantially greater when for the purpose of increasing the tensile strength of the longitudinal ribs a thicker sheet is used since herein in this case the thickness of the cross-ribs is also forced unnecessarily to be increased which ribs do not need to absorb any or only slight tension forces.

SUMMARY OF THE lNVENTlON It is an object of the invention to provide structural elements of a plate-like form which although of slight weight can absorb large tension forces in the direction of the longitudinal ribs. This makes it possible to attain, inter alia, a range of uses of the structural element for stressed steel concrete bodies in structures above ground level.

The invention provides a plate-like structural element for concrete structures utilizable as lost shuttering and reinforcement which comprises a platelike structural element for concrete structures, utilizable as lost shuttering and as reinforcement, which comprises a plurality of reinforcing steel rods arranged as spaced apart parallel longitudinal rods in planar form, and a plurality of strip-like cross-ribs connected to said longi tudinal rods, the cross-ribs being arranged parallel to one another and bent outwardly between each rod in a direction perpendicular to the plane of the assembled rods, the said outward deflection being in opposed perpendicular directions with alternate strip-like crossribs. 1

As a result of the use of the reinforcing steel longitudinal rods, instead of the sheet corrugations as longitudinal ribs which are weakened through notch effect, for the same cross-sectional surface of the longitudinal rods or ribs there is given a considerable increase of the tensile strength in the longitudinal direction. The use of the longitudinal reinforcing steel rods has furthermore the advantage that the rods do not suddenly break off under stronger loading as is the: case with sheet corrugations weakened through notch effect. One can therefore in the static reckoning count on the same safety factors as are applied normally in the usual reinforcement with reinforcing steel rods. In reinforcement with the known corrugated sheets, on the contrary, a substantially higher safety factor had to be applied. Since the reinforcing steel rods do not suddenly rupture under over-loading, as occurs through the notch effect with weakened sheet corrugations, but deform plastically at first in a relatively large zone, the over-loading of the reinforcement is indicated by cracks in the concrete body before the reinforcement is completely destroyed. Thus this gives an advantage in contrast to the reinforcement by the known corrugated sheets. A further advantage is given in that in the structural elements in accordance with the invention the thickness of the cross-ribs can be selected fully independently of the requisite cross'sectional surface of the longitudinal ribs. Since for most uses the tensile strength of the structural element in the direction of the cross-ribs need amount to only 20 percent of the tensile strength in the direction of the longitudinal ribs, there can be attained by suitable selection of the thickness of the cross-ribs a considerable diminution of the total weight of the structural element. In accordance with the invention structural elements of plate-like structure are thus possible which have with slighter weight better static properties than the known corrugated sheet structural elements.

According to a particularly preferred embodiment of the invention the cross-ribs consist of continuous steel strips which, between the. longitudinal rods, are curved in the same direction perpendicular to the plane of the plate and can have the shape of corrugations. Accordingly in that the cross-ribs consisting of continuous steel strip are curved in the same direction perpendicular to the plane of the plate, it is possible when placing neighboring plates to allow them to overlap one another without hindrance through the bow-shaped crossribs.

On the same ground the cross-ribs are preferably spaced from one another in the direction of the longitudinal ribs, the spacing amounting to at least two millimeters. This ensures that the cross-ribs of over-lapping plates can engage unhindered in one another with some clearance without the breadth of the cross-ribs having to be alteredover their length.

The use of continuous steel strip as cross-ribs makes possible also a particularly simple production of the structural element. For this purpose machines can be used, which operate on the same principle as machines for the production of conventional structural steel webs. This is of particular advantage in that there is no compulsion in production to use a predetermined sheet format, but the dimensions of the plate-like structural element can be readily varied. For simplified production it is also provided that the longitudinal rods and the cross-ribs are secured to one another by spotwelding and that all cross-ribs are fastened on the same side to the longitudinal rods.

The last-mentioned characteristic also provides the advantage that all longitudinal rods are on one side of the structural element. This makes possible an especially good embedding of the longitudinal rods, serving as reinforcement, in the concrete mass. In order to attain a good adhesion of the longitudinal reinforcing steel rods these can have a profile preventing slippage between the concrete and the rod.

In order to facilitate a good tensile connection, in the direction of the longitudinal rods, between two platelike structures, the longitudinal rods project from the outermost cross-ribs on one or both sides by a distance equivalent to about 30 to 40 times their diameter. In placing the plate-like structures edge to edge the projecting end sections of the longitudinal rods project far enough into the steel concrete body reinforced by the neighboring plates so that a static troublefree connections results, without the cross-ribs overlapping in the direction of the longitudinal rods.

In an alternative embodiment of the invention the cross-ribs are made as synthetic material profiles. By the use of synthetic material strips in place of steel strips a considerable weight reduction and cheapening of the structural element is attained. The development of the invention makes use of the knowledge that the strip-shaped cross-ribs have essentially only the function of a shuttering and have to absorb in their longitudinal direction only slight or no tension forces. The tensile strength of the structural element in the direction of the longitudinal rods is also fully maintained with the use of synthetic material cross-ribs.

Suitably the synthetic material cross-ribs are provided with fastening means for fastening to' the longitudinal rods. These fastening means can for example be made as clamps, straps or the like and may be integral with the cross-ribs or may be made as separate parts.

In a particular embodiment using synthetic material cross-ribs these may be constructed as T-profiles in the web of which cut out portions, for example, holes or slots are provided for reception of the longitudinal rods. This makes possible a particularly simple and durable connection between the longitudinal rods and the cross-ribs.

Furthermore, the cross-ribs can be fastened by glueing to the longitudinal rods. The glue connection may be used in place of the above-described fastening means, but can also be additional to the abovedescribed types of fastening. This will thus give a particularly firm connection between the longitudinal rods and the cross-ribs.

In order to increase the tensile strength of the structural element in the direction of the cross-ribs the cross-ribs can be fiber-reinforced in their longitudinal direction. Reinforcement may be by glass fibers, metal threads or the like.

In order to prevent slippage between the cross-ribs and the surrounding concrete mass the surface of the cross-ribs may also be roughened or profiled.

For different uses the reinforcement in the direction of the cross-ribs must have a tensile strength which corresponds to the tensile strength in the direction of the longitudinal rods. In order to fulfil this requirement it is provided that the longitudinal rods are connected by additional strengthening ribs, which lie in the direction of the cross-ribs, but at greater spacing from one another, and which consist of strip-like or rod-like reinforcing steel. These strip-like or rod-like strengthening ribs are connected with the longitudinal rods by spotwelding. If they are formed as relatively thin wires they can be also fastened to the longitudinal ribs by winding around them.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a section through a plate-like structural element perpendicular to the direction of the longitudinal rods,

FIG. 2 is a plan view of the structural element according to FIG. 1 from the side on which the longitudinal rods are fastened,

FIG. 3 is a section through a plate-like structural element, according to another embodiment of the invention, perpendicular to the direction of the longitudinal rods,

FIG. 4 is a plan view of the structural element according to FIG. 3 from the side on which the longitudinal rods are fastened,

FIG. 5 is a cross-section through a cross-rib with the longitudinal rods fastened thereon and FIG. 6 is a cross-rib in side view showing different reception openings for the longitudinal rods.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1 and 2 the longitudinal rods of reinforcing steel are indicated by reference numeral 1 and the cross-ribs of continuous steel strip indicated by reference numerals 2 and 3. The cross-ribs 2 are all curved between the longitudinal rods in the one direction perpendicular to the plane of the rod assembly whilst the cross-ribs 3 are all curved in the other perpendicular direction.

The cross-ribs 2 and 3 are all fastened to the same side of the longitudinal rods 1. The connection between the longitudinal rods 1 and the cross-ribs 2 or 3 is produced by spot-welding. The spot-welding is advantageous for the connection in so far as no structural alterations substantially affecting the tensile strength in the longitudinal rods are to be feared.

Between the cross-ribs 2 and 3 a clearance of at least 2 millimeters is allowed, accordingly with over-lapping setting of the structural elements the bow-shaped crossribs 2 or 3 can fit in one another with a certain clearance.

The longitudinal rods project from the outermost cross-ribs to about 30 to 40 times their diameter in order to make possible a trouble-free connection between neighboring elements.

The longitudinal rods of reinforcing steel have either, as shown in the drawing, circular cross-section or they can have other cross-sectional shapes and particularly such shapes as will prevent a slippage between the concrete and the rod embedded therein. A torsioned profile of rod is particularly suitable for this purpose, the

profile of which has sharp-edged projections at the periphery.

In order possibly to increase the bending resistance of the strip-shaped cross-ribs, they can in contrast to the shape illustrated in the drawing be shaped as corrugations. Obviously the plate-shaped structural elements can be also shaped as a whole in such a way that they are adapted for example for shuttering and for reinforcement of curved or pillar-shaped steel reinforced concrete bodies.

In FIGS. 3 and 4 the longitudinal rods of reinforcing steel are indicated by the reference numeral 11 and the cross-ribs of continuous synthetic material profiles are indicated by reference numerals I2 and 13. The cross ribs 12 are all curved out between the longitudinal ribs in the one direction perpendicular to the plane of the assembled rods, while cross-ribs 13 are all curved out in the other perpendicular direction.

The cross-ribs l2 and 13 are all fastened to the longitudinal rods 11 on the same side. The connection between the longitudinal rods 11 and the cross-ribs 12 or 13 is illustrated in detail in FIGS. 5 and 6. The cross-rib 12, indicated here, is made as a T-profile, the web of which is indicated by reference numeral 12a. In the web 12a reception holes 12b or reception slots 12c are arranged which serve for reception of the longitudinal rods 1 1. Instead of the type of fastening shown in FIGS. 5 and 6, cross-ribs l2 and 13 respectively of synthetic material can also be glued to the longitudinal rods 11, or can be connected with the help of other suitable fastening means. Glueing can also be used in addition to the other kinds of fastening. The cross-ribs 13 are likewise fastened through their web 13a to the longitudinal rods 11 as described for the cross-ribs 12 in FIGS. 5

and 6.

The cross-ribs l2 and 13 respectively can be fiberreinforced in their longitudinal direction. In addition the surfaces of the cross-ribs l2 and 13 respectively can be roughened or provided with a special profile so that a good connection is assured with the embedding concrete.

For strengthening the tensile strength of the structural elements in the direction of the cross-ribs the longitudinal rods are additionally connected through strengthening ribs 14, which may be in the form of reinforcing steel rods and are fastened to the longitudinal rods by spot-welding. The spot-welding is advantageous for the'connection in so far as no structural changes substantially affecting the tensile strength in the longitudinal rods 11 or the strengthening ribs 14 are to be feared. The strengthening ribs are suitably secured to the longitudinal rods on the side which is turned towards the hollow space to be filled with concrete. A particularly good embedding of the strengthening ribs in the concrete body is thus assured. v g

In place of the rod-like strengthening ribs I4, striplike strengthening ribs 14 can also be used. Furthermore it is possible to use, in place of the strengthening ribs at greater spacing, cross-ribs 12 or 13 of strip steel which secure the requisite tensile strength of the structural element in the direction of the cross-ribs.

I claim:

1. A plate-like structural element for concrete structures, utilizable as a lost shuttering and as reinforcement, which comprises a plurality of reinforcing steel rods arranged as spaced apart parallel longitudinal rods in planar form, and a plurality of strip-like cross-ribs, means connecting said cross-ribs to said longitudinal rods at one side thereof only, the cross-ribs being arranged parallel to one another and being bent between adjacent rods to form a single half loop between adjacent rods, said half loops lying in a plane perpendicular to the plane of the assembled rods, the said half loops in each cross-rib lying in the same direction with the half loops of adjacent cross-ribs lying in the opposite direction so that two offset contiguous half loops of adjacent cross-ribs form a single complete loop, said rods being disposed exteriorly of said complete loops, and said complete loops being adapted to receive concrete with the full lengths of said reinforcing steel rods embedded in the concrete outside of the loops.

2. A plate-like structural element in accordance with claim I, wherein the cross-ribs consist of continuous steel strips.

3. A plate-like structural element for concrete structures according to claim 1, wherein said means connecting said cross-ribs to said longitudinal rods comprises spot welding at the same side of the longitudinal rods.

4. A plate-like structural element according to claim 1, wherein said means connecting said cross-ribs to said longitudinal rods comprises a plurality of strip-like members each integrally formed with a cross-rib longitudinally thereof so that the combined strip members and cross-ribs are each T-shaped in cross-section, and cut-out portions provided in said strip members for reception of said reinforcing steel rods.

5. A plate-like structural element according to claim 4, wherein said cut-out portions in said strip members are circular openings therein.

'6. A plate-like structural element according to claim 4, wherein said cut-out portions are slots in the strip members extending inwardly from the unattached edges thereof.

7. A plate-like structural element in acc ordance with claim 1, wherein said cross-ribs are formed of synthetic material and wherein said means for fastening the cross-ribs to the longitudinal rods comprises glue.

8. A plate-like structural element in accordance with claim 1, wherein the strip-like cross-ribs are spaced from each other in the direction of the longitudinal rods by at least 2 millimeters.

9. A plate-like structural element in accordance with claim I wherein the longitudinal rods extend beyond an outermost strip-like cross-rib. by a distance equivalent to about 30 to 40 times their diameter.

10. A plate-like structural element in accordance with claim 1 wherein the strip-like cross-ribs are made of synthetic material, which may be fiber-reinforced in their longitudinal direction.

terial and wherein the longitudinal rods are connected by additional strengthening ribs lying in the direction of the cross-ribs but spaced apart at greater intervals, said additional strengthening ribs being made from reinforcll. A plate-like structural element in accordance ing steel in the form of strip or rod.

with claim 1 wherein the cross-ribs are of synthetic ma- 

1. A plate-like structural element for concrete structures, utilizable as a lost shuttering and as reinforcement, which comprises a plurality of reinforcing steel rods arranged as spaced apart parallel longitudinal rods in planar form, and a plurality of strip-like cross-ribs, means connecting said crossribs to said longitudinal rods at one side thereof only, the cross-ribs being arranged parallel to one another and being bent between adjacent rods to form a single half loop between adjacent rods, said half loops lying in a plane perpendicular to the plane of the assembled rods, the said half loops in each cross-rib lying in the same direction with the half loops of adjacent cross-ribs lying in the opposite direction so that two offset contiguous half loops of adjacent cross-ribs form a single complete loop, said rods being dIsposed exteriorly of said complete loops, and said complete loops being adapted to receive concrete with the full lengths of said reinforcing steel rods embedded in the concrete outside of the loops.
 2. A plate-like structural element in accordance with claim 1, wherein the cross-ribs consist of continuous steel strips.
 3. A plate-like structural element for concrete structures according to claim 1, wherein said means connecting said cross-ribs to said longitudinal rods comprises spot welding at the same side of the longitudinal rods.
 4. A plate-like structural element according to claim 1, wherein said means connecting said cross-ribs to said longitudinal rods comprises a plurality of strip-like members each integrally formed with a cross-rib longitudinally thereof so that the combined strip members and cross-ribs are each T-shaped in cross-section, and cut-out portions provided in said strip members for reception of said reinforcing steel rods.
 5. A plate-like structural element according to claim 4, wherein said cut-out portions in said strip members are circular openings therein.
 6. A plate-like structural element according to claim 4, wherein said cut-out portions are slots in the strip members extending inwardly from the unattached edges thereof.
 7. A plate-like structural element in accordance with claim 1, wherein said cross-ribs are formed of synthetic material and wherein said means for fastening the cross-ribs to the longitudinal rods comprises glue.
 8. A plate-like structural element in accordance with claim 1, wherein the strip-like cross-ribs are spaced from each other in the direction of the longitudinal rods by at least 2 millimeters.
 9. A plate-like structural element in accordance with claim 1 wherein the longitudinal rods extend beyond an outermost strip-like cross-rib by a distance equivalent to about 30 to 40 times their diameter.
 10. A plate-like structural element in accordance with claim 1 wherein the strip-like cross-ribs are made of synthetic material, which may be fiber-reinforced in their longitudinal direction.
 11. A plate-like structural element in accordance with claim 1 wherein the cross-ribs are of synthetic material and wherein the longitudinal rods are connected by additional strengthening ribs lying in the direction of the cross-ribs but spaced apart at greater intervals, said additional strengthening ribs being made from reinforcing steel in the form of strip or rod. 